1. Field of the Invention
The present invention relates to an optical printer with a color filter and optical printing method, and more particularly, relates to an optical printer with a color filter and optical printing method in which printing light is applied to color photosensitive material to print a color image, and in which such an image can be printed efficiently.
2. Description Related to the Prior Art
An optical printer is a known device in which printing light of plural colors is applied to color photosensitive material for printing a color image thereto. The optical printer has a printing head, which includes a light source of white light and a color separation filter unit. The color separation filter unit is constituted by plural color filters of red, green and blue colors for converting light from the light source into the printing light of the red, green and blue colors. The printing head has a length of one line included in the color image, and is disposed to extend in a main scan direction. To record an entire frame of the color image, the printing head is moved relative to the color photosensitive material in the sub scan direction.
JP-A 11-127409 (corresponding to WO 99/21055) discloses a combined structure in which the optical printer is incorporated in an electronic still camera. An instant photo film is used as the color photosensitive material in the optical printer, which operates according to frame-sequential printing. The frame-sequential printing is a method in which colors are recorded frame after frame to obtain the color image. At first, a red one of the color filters is set in a light path. The printing head is moved in the sub scan direction, to record one red frame by use of red printing light. Then a green one of the color filters is set in the light path. The printing head is moved in the sub scan direction, to record one green frame by use of green printing light. After this, a blue one of the color filters is set in the light path. The printing head records one blue frame by use of blue printing light, to obtain the color image. Spreader rollers are operated to break a processing solution pod contained in the instant photo film, spread processing solution over an exposure surface to process the color image. The instant photo film is ejected at the same time.
The color separation filter unit has a plate shape in which the color filters are arranged adjacently to one another. The color separation filter unit is slid to set a selected one of the color filters in the light path.
However, the optical printer for the frame-sequential printing has shortcomings in efficiency. The instant photo film cannot be advanced toward the outside of the optical printer after the completion of three-color exposure. The printing head must be moved during recording. A space must be kept enough for moving the printing head. Also, a head moving mechanism is required for the printing head, and may cause the optical printer to have a considerably large size. Furthermore, a problem of the frame-sequential printing in the full color lies in very long time required for printing, as the printing head is moved back and forth for frames of three colors.
In view of the foregoing problems, an object of the present invention is to provide an optical printer and optical printing method in which printing light is applied to color photosensitive material to print a color image, and in which such an image can be quickly printed with a simple structure.
In order to achieve the above and other objects and advantages of this invention, an optical printer records a color image by exposing color photosensitive material extending two-dimensionally in a main scan direction and a sub scan direction. The optical printer comprises a printing head, which includes a light source and a color separation filter unit. The color separation filter unit is disposed in a light path of light from the light source, for color separation of the light from the light source, the color separation filter unit having a tubular shape, having a central axis extending substantially parallel with the main scan direction, being rotatable about the central axis, and into which the light from the light source travels through an entrance position along the light path, and out of which the light from the light source travels through an exit position along the light path. The color separation filter unit includes plural color filters, arranged about the central axis, having selectivity of a wavelength, for converting the light from the light source into printing light of respectively single colors, the plural color filters being so disposed that a single one thereof is in the entrance position or the exit position in a manner irrespective of a rotational position with reference to the central axis. Plural transmission portions or openings are arranged alternately with the plural color filters.
Furthermore, a filter drive mechanism rotates the color separation filter unit. A light amount adjustor adjusts a light amount of the printing light by each of pixels. A controller causes the filter drive mechanism to set in the light path a color filter among the plural color filters associated with a respective color to be recorded, and for operating the light amount adjustor according to density of the pixels of the respective color while the color filter is set in the light path.
The printing head is stationary. Furthermore, a feeder feeds the color photosensitive material in the sub scan direction, to cause the printing head to record the color image to the color photosensitive material.
The exit position is opposed to the entrance position with reference to the central axis. A total number of the plural color filters and the transmission portions or openings is 6(2n+1) where n is an integer equal to or more than zero, and the transmission portions or openings are opposed to respectively the plural color filters with reference to the central axis.
According to another preferred embodiment, furthermore, a reflector is disposed in the color separation filter unit, for reflecting light from the entrance position to cause the light to travel to the exit position.
The reflector is so disposed that the light from the entrance position is reflected substantially at a right angle to travel to the exit position. A total number of the plural color filters and the transmission portions or openings is 12(2n+1) where n is an integer equal to or more than zero.
The color separation filter unit further includes at least one ND filter for reducing the light amount of the printing light of at least one of the single colors.
The at least one ND filter is plural ND filters for constituting the plural transmission portions.
According to another preferred embodiment, the at least one ND filter is plural ND filters disposed to lie on respectively the plural color filters.
The color separation filter unit has a cylindrical shape.
According to another preferred embodiment, the color separation filter unit has a prismatic shape.
The light amount adjustor comprises a micro shutter, disposed in the light path, and of which transmittance density is variable by each of the pixels.
According to another preferred embodiment, the light source includes an array of plural light-emitting elements.
The light amount adjustor comprises a light-emitting element driver for driving the plural light-emitting elements by applying energy thereto according to the pixel density.
Furthermore, an encoder plate is secured to the color separation filter unit, has color information disposed in association with the plural color filters, for representing colors of the plural color filters. A phase detecting sensor reads the color information to recognize a color of one of the plural color filters set in the light path. The controller controls the light amount adjustor according to signal from the phase detecting sensor.
The plural color filters are disposed with respectively a first central angle about the central axis in the color separation filter unit. The color information is disposed with respectively a second central angle about a central axis in the encoder plate, the second central angle being smaller than the first central angle. The controller sends an image signal to the light amount adjustor, and the image signal starts being output after a portion of respectively the plural color filters comes in the light path, and finishes being output before an entirety of respectively the plural color filters comes out of the light path.
According to another preferred embodiment, the filter drive mechanism includes a stepping motor. The controller controls the stepping motor to set in the light path one of the plural color filters having a color of the printing light of which the light amount is to be adjusted.
The color photosensitive material is an instant photo film.
According to another aspect of the invention, an optical printer records a color image by exposing a color photosensitive material. The optical printer comprises a printing head, which includes a light source and a color separation filter unit. The color separation filter unit is disposed in a light path of light from the light source, for color separation of the light from the light source. The color separation filter unit includes plural color filters, arranged in a manner adjacent to one another in a plate shape, having selectivity of a wavelength, set in the light path sequentially, for converting the light from the light source into printing light of respectively single colors. At least one ND filter, disposed to lie on at least one of the plural color filters, for reducing the light amount of the printing light of at least one of the single colors.
The color photosensitive material extends two-dimensionally in a main scan direction and a sub scan direction, the color separation filter unit extends substantially parallel with the main scan direction, and the plural color filters are arranged in an arranging direction crosswise to the main scan direction. Furthermore, a filter sliding mechanism slides the color separation filter unit in the arranging direction.
The plural color filters are included in a single piece.
According to still another aspect of the invention, an optical printing method of recording a color image by exposing a color photosensitive material comprises the following steps. Light from a light source is converted into printing light of plural colors by filtering. A light amount of the printing light of the plural colors is controlled according to an image signal. The light amount of the printing light of at least one of the plural colors is reduced by filtering.